Core for tubular ingot molds



Nov. 4, 1952 B. BROWNSTEIN CORE FIOR TUBULAR INGOT MOLDS 2 SHEETS--SHEET Filed Dec. 29, 1949 Benjamin Brownslein Patented Nov. 4, 1952 UNITED STATES PATENT OFFICE CORE FOR TUBULAR INGOT MOLDS Benjamin Brownstein, Ellwood City, Pa.

Application December 29, 1949, Serial No. 135,655

7 Claims.

This invention relates to the art of making hollow or tubular cast ingots, as a preparatory step to the forming of seamless tubes, pipe or hollow shafting.

As is well known the casting of hollow or tubular ingots around metal cores is extremely difficult and the results highly unsatisfactory because of the fact that the molten metal while cooling and solidifying contracts and binds on or freezes to the metal of the core so that its subsequent removal from the core is extremely difficult and also the heating of the core to a high temperature causes it to soften and become distorted in shape. The distorted condition of the core also adds to the difficulties of removing the core from the ingot.

Another difliculty associated with the formin of cast tubular ingots is the development of cracks in the interior surface of the wall of the cored hole.

The basic requirements for a perfectly cast tubular ingot from which tubular goods may be manufactured, are that;

First, a cast tubular ingot with a cored hole must have the interior surface of the wall entirely free from shrinkage cracks, blow holes, sand holes, fused sand, etc., and must be smooth. Second, the core must be easily removed and leave a clean smooth interior surface in the ingot.

Any cast tubular ingot with a cored hole, failing in any or all of the above enumerated requirements, cannot be used for rolling into a tube or pipe and must be rejected.

When shrinkage cracks develop in the interior surface of the wall of the cored hole, and the core is removed, the cracks become filled with scale due to the oxidation of the metal, and the metal in the cracks can never become welded into a homogeneous mass no matter how much heating and rolling or forging theingot undergoes.

The interior surface of the hole in the ingot becomes a part of the finished rolled tube or pipe, and all the defects that the tubular cast ingot has, the finished rolled tube or pipe will have and many times more magnified due to the rolling action of the fabrication for producing a tube or pipe.

Many attempts have been made to produce cast tubular ingots with the use of cores made from sand or other similar materials and all have failed due to the development of some or all of the above enumerated defects, and the great difliculty of removing sand from the interior surface of the ingot.

A cast iron core cannot be used, even though it should not distort (which it always does) because, it is gripped so hard by the shrinking metal as it cools that it becomes impossible to remove the metal core from the cooled ingot.

In the light of the foregoing the principal object of the present invention is to provide an improved apparatus whereby a tubular ingot may be cast which is entirely free from all of the above enumerated defects.

Another object of the invention is to provide a defect free cast tubular ingot by the provision of apparatus employing a flexible or yieldable core, as a result of which the contraction of the metal in the mold about the core will not result in the freezing of the ingot to the mold or the core to cause difficulty in removing the core from the ingot.

Other objects and advantages of the invention will become apparent as the description of the same proceeds and the invention will be best understood from a consideration of the followin detailed description taken in connection with the accompanying drawings with the understanding, however, that the invention is not to be limited to the exact details of construction shown and described since obvious modifications will occur to a person skilled in the art.

In the drawings:

Figure 1 is a view in top plan of a preferred embodiment of the present invention.

Figure 2 is a vertical central section taken substantially on the line 2-2 of Figure 1.

Figure 3 is a horizontal section on an enlarged scale taken on the line 3-3 of Figure 2.

Figure 4 is a horizontal section taken on the line 44 of Figure 2.

Figure 5 is a horizontal section taken on the line 5-5 of Figure 2 in the central part of the apparatus.

Figure 6 is a fragmentary sectional detail taken on the line 6-6 of Figure 3.

Referring more particularly to the drawings the numeral H] generally designates the ingot stool upon which the ingot is cast. This stool has a top floor portion H which is of circular form and defined by the beveled or outwardly.

and downwardly sloping shoulder I2.

Formed in the center of the stool andopening through the center of the floor II is a centering hole l3 through the bottom of which is formed the opening M which is of smaller diameterthan the hole l3.

The wall of the hole l3 at the top thereof is reamed or beveled as indicated at l5, for the pur pose hereinafter described.

The numeral 16 generally designates the ingot mold which, as shown, is open top and bottom 3 and has the upwardly tapering inner wall l1 which facilitates the lifting of the mold from the cast ingot.

The bottom end of the mold l5 rests upon the floor I! at the periphery thereof as shown and has the downwardly extending or inclined lip i8 which conforms to the bevel l2 over which it lies.

At the top end the mold it has formed around the inside thereof the recess l9 having the outwardly flaring or downwardly tapering wall 20.

Adapted to rest in the annular recess 59 is a centering ring 2! which is provided with the outside tapering face 22 which corresponds to the taper of the wall 28. This centering ring supports by means of the upwardly and inwardly directed arms 23, a core centering yoke which is generally designated 24 and which, when in position in the set-up apparatus, is concentric with the bottom centering hole l3.

The numeral 25 generally designates a bottom centering sleeve which is of cylindrical form and having an outside diameter somewhat less than the inside'diameter or" the hole 13 whereby the sleeve, when positioned in the hole, will have an appreciable clearance between it and the hole wall. This sleeve has an axial passage 26 therethrough and at its top is provided with an encircling shoulder 2'! which is inclined inwardly slightly, by the provision of which shoulder there is produced the central upstanding collar 2%.

When the bottom centering sleeve is in position in the hole [3 the shoulder 21 will be at an elevation slightly below the floor I l and the portion 28 will project slightly above the level of the 11061.

As shown in Figure 5 this bottom centering sleeve is here disclosed as being longitudinally divided or split into the two halves 25a and 251), one of which parts is provided with the tangential recesses'25c to receive the heads of bolts 29 whichsecure the two parts together. While this bottom centering sleeve has been shown as being in two parts it is to be understood that the invention is not limited to this construction since such sleeve may be made as a solid body if desired.

The numeral 38 generally designates a solid metal centering cone which has-anovcrall length approximately equalling the height of the ingot mold. The bottom or smaller end of this tapered body or cone 39 1s of a diameter approximating the diameter of the extended top portion 28 of the bottom centering sleeve and thelower part of the circular extension 280i ith'ebottomcentering sleeve has approximately the same taper as the cone 30 whereby the hereinafter described asbestos sleeve which is placed around the cone 30 will tightly embrace or-h-ugthe lower part of the extension 28 and the cone, without distortion.

Extending axially from the lower end-of the cone 30"is a long stem 3"! which has a snug sliding fit in the bore 26 of the bottom centering sleeve and which, when the bottom end of the cone 30 is resting upon thetop of the bottom centering sleeve, has its lower end projected a substantial distance below the opening [4. Upon the lower end of the stem 31 is fixed a member, here shown as a nut 32, which is adapted to pass through the opening [4 to have contact with the bottom of the bottom centering sleeve whenthe centering cone is being withdrawn'from a cast ingot.

The top end of the centering cone 341 has extending axially therefrom the upper or top stem 33. This stem is here shown as having a tapped V axial bore 34 formed in the 'topend tliereof to receive the threaded stud 35 which forms a part of a crane hook connecting eye 36. s

The numeral 3'! generally designates the top centering sleeve which, as shown in Figure 4, is here illustrated as being divided longitudinally to form the two sections 31a which are secured together by bolts 38 passing through the radial cars 39 carried by each of the sections.

The top centering sleeve 31 has a top collar portion 48 which fits snugly within the centering yoke 24 and has the top stem 33 passing therethrough as shown.

The top centering sleeve is designed with a circular downwardly opening chamber 4! into which the upper end or large end of the cone 3%] projects and into which it moves upwardly when the cone is being withdrawn from a cast ingot.

The lower part of the wall of the centering sleeve chamber 4| is cut out or recessed as indicated at 42 to receive the top end of the flexible core structure about to be described.

When the apparatus is set up for use the cone 3%] has wrapped around it throughout its entire length, a conical tube 53 made up from plain and corrugated asbestos paper, with the corrugations 24 running lengthwise of the tube.

Around this conical tube 43 are wound two or more layers of rope 35 of an insulating heat resisting fiber such as asbestos. These ropes are wound around the paper tube in a spiral with the spirals of the difierent layers crossing one another.

These spiral wound layers of asbestos rope are cemented together and to the asbestos conical tube, with asbestos cement which is designated 38 and which completely fills the spaces between the convolutions of therope as is clearly illustrated in Figures 2 and 6. Also the asbestoscement is applied over the entire outer layer of asbestos rope as is clearly shown in the figures referred to so that there is provided a smooth tapering outside surface for the rope layers.

As is clearly shown in Figure 2 when the asbestos paper cone is placed in position and the layers of asbestos fiber coated with and cemented together with asbestos cement, are set up, there is provided a relatively solid flexible core 4'! which has an inside and outside taper corresponding to the taper of the cone 3% and the lower end of this flexible core encircles the extension 28 of the bottom centering sleeve and rests uponthe shoulder 27. The top end of the core will be engaged in the channel 42 of the top centering'sleeve when the apparatus is completely set up ready for the casting operation.

To complete the flexiblecor'e, after the outside surface 'is made smooth, it has applied thereto a coating or layer 48 of graph-it'epowder.

While the top centering sleeve has been shown and described as being longitudinally divided into two parts which are secured together by the bolts 38, it is to be understood that the invention is not limited to this construction since, by the use of the detachable crane hook connecting eye 36, the stem 3Zlcould be extended through a passage in a solid centering sleeve and accordingly it will be understood that such solid sleeve maybe used in place of the two-.part s'leeve here-shown where the removable eye is employed. The eye 'tt-a'nd the top stem 33 may, however, be formed as a solid piece with the. cone 3B, in which case the two-part top centering'sleeve would berequired.

The procedure follcwed; in setting up the apparatus as it is shown in Figure 2, is as follows:

On the bottom of the centering hole [3 a layer 49 of asbestos powder is spread to act as aheat insulator between the bottom centering sleeve and the stool. The Wall of-the-hole 13 is then coated with graphite as indicated at 50, which acts as a lubricant to allow the centering sleeve to slip in easily.

The bottom centering sleeve of the flexible core 41 as it is assembled, is lowered into the centering hole and when it reaches the bottom the flexible core becomes fixed in the stool and the centering cone is then lowered to rest on the top extension 28 of the centering sleeve.

In order to make a tight liquid joint between the bottom end of the flexible core and the stool, the annular cavity formed around the top of the centering sleeve by the bevel I5 at the top of the centering hole, is filled with asbestos cement as indicated at 5|. 7 After the flexible core 41 is located in the stool with the centering cone 30 lowered so that it rests on the part 28 of the centering sleeve and is cemented in the stool, the mold I6 is located and centered on the shoulder l2 of the stool floor, after which the top centering ring 31 is placed in position upon the top end of the flexible core structure, with the top stem 33 extending through the collar portion 40 of the top centering sleeve.

The centering ring 2| and centering yoke 24 are then placed in position, the ring 2| being disposed within the annular recess in the top of the mold. Before placing the ring 2| in the recess I9, the beveled wall of the recess has a coating of asbestos powder 52 applied thereto, upon which the beveled face of the ring 2| rests. This powder acts as a heat insulator between the mold and the ring. It will be readily apparent that when the centering ring is placed in position the yoke 24 will engage around the collar 40 to securely hold the top centering ring, the cone 30 and flexible core 41 in the exact center of the mold. This arrangement makes a positive centering means for keeping the flexible core in position, which is very important because only a small eccentricity of the passage or opening in the ingot will make the ingot unfit for the formation therefrom of tube and pipe products.

In addition to the placing of the asbestos coating between the faces 20 and 22 of the mold and centering ring respectively a coating or layer of asbestos powder may be placed on the floor surface beneath the bottom edge of the mold as indicated at 53.

The pouring of the hot molten metal into the mold is done in the usual way and left to cool and solidify until the hot metal reaches a predetermined temperature. The cast tubular ingot is then ready for the removal of the flexible core, which is accomplished as follows.

The hook of a lifting crane is engaged with the eye 36 at the centering cone and the cone is raised or lifted until the nut 32 at the end of the extension 3| comes into contact with the bottom of the bottom sleeve 25. This action effects the loosening of the cone in the conical tube, as will be readily apparent thus separating the cone from the flexible core. This movement of the centering cone relieves the pressure produced by the weight of the hot metal and shrinkage strains on the flexible core.

The raising of the centering cone is continued and this action causes the bottom centering sleeve 25 to raise the flexible core and removes it from the cast tubular ingot. As will be readily apparent the top centering sleeve and the yoke and ring are also removed during this operation.

The flexible core is easily removed from the cast ingot after the ingot has cooled to the proper temperature, leaving a fine smooth surface in the cored hole of the ingot. The ingot is then stripped from the mold and charged into the soaking pit furnace, reheated and rolled directly into a tube or pipe by the use of a continuous, rolling mill and mandrel bar such as is disclosed in my prior Patents Nos. 2,140,414 and 2,025,439. In this manner a very cheap seamless tube or pipe of any length is produced. The long length pipe may then be cut into shorter lengths as required without waste.

It will be readily noted that the design of the ingot molding apparatus is such that all expansion clue to the heating of the parts is taken care of.

When thehot molten metal is poured into the mold and it makes contact with the top part or floor of the stool, it causes the stool floor to expand and since such floor part is formed with a beveled shoulder of approximately 45 to fit into the bottom of the mold, the heating and expanding of the floor has no effect on the mold which in turn soon heats up from the metal therein. The bottom centering sleeve 25 will heat up to a lesser degree as a result of it not being directly in contact with the stool and because of the fact that it is made a little smaller than the centering hole, for clearance. In time it will expand due to the heat but it will not exceed the clearance between the sleeve and the hold, therefore, the sleeve will be free in the hole and can be removed easily when necessary.

The yoke and ring will also heat up but not to a great extent because of the fact that the asbestosinsulation between the ring and the top of the mold prevents direct contact of metal with metal. The top centering sleeve willnot absorb much heat from the flexible core and the expansion due to the heat that it will get from theyoke will not cause it to expand more than the yoke and the clearance will take care of the easy movement necessary inthe yoke.

It will be seen from the foregoing that the flexible core is easily removed from the cast ingot after the ingot has cooled to the proper temperature, leaving a smooth surface in the cored hole of the ingot.

The present apparatus and method of using the same, constitutes a decided improvement over the method and apparatus disclosed in my prior Patents Nos. 1,912,965 and 1,912,966 by reason of the fact that the present apparatus eliminates the expensive piercing press with all auxiliary equipment, hydraulic pumping system, etc., and the cost of their operation. In their place there has been developed in the present apparatus a simple flexible core which is easily extracted from the ingot after it has cooled to the proper temperature.

With the present apparatus ingots of practically any size can be cast. Large ingots of from 5,000 to 30,000 pounds or more cannot be rolled on any present rolling mills in this or any other country other than a rolling mill with the mandrel bars as disclosed in my prior patents hereinbefore referred to. These mills are capable of handling ingots of these large sizes. While smaller ingots are readily cast with the present equipment the gain in production and cheapness occurs primarily in connection with the casting and rolling of large ingots in the range of sizes above set forth.

I claim:

1. Apparatus for casting tubular metal ingots, comprising an ingot stool, an upright cylindrical mold thereon, the stool having a central hole lying in the axial center of the mold and said hole having a central bottom opening, a'bottom center ing sleeve. in said :hole, the sleeve having an axial passage aligning with said bottom opening, a top centering sleeve having a downwardly opening chamber, means maintaining the top centering sleeve coaxial with the bottom centering sleeve, a vertical downwardly tapering metal core body restingupon' the bottom centering sleeve and-havingits upper end positioned and-of adiameter to enter, when raised, into said top centering sleeve chamber, the top centering sleeve having an axialpassage through the top thereof, axial stems carried by "the top and bottom ends of th core and freely passing respectively through the top centering sleeve passage and the bottom centering sleeve passage, the bottom stem extending beyond the bottom of the bottom sleeve; means on the lower end of the bottom sleeve stem adapted to pass through the bottom opening of the-hole but preventing withdrawal'of the. bottom sleeve stem from the bottom sleeve, means carried by' t'he top stem for facilitating the lifting of the core, and a jacket of heat resisting material encasing the core and held between the top and bottom centering sleeves.

2'. The invention according to claim I, with an upwardly tapering annular rib upon the top of and concentric with the bottom centerings'leeve and of smaller overall diameter than th'ebo'ttom sleeve, said rib providing a centering means for said jacket 3. 'The invention according 'to claim 2,, wherein they top edge of the central hole in the stool is beveled ofi to a depth below the top of the'bottom centering sleeve to form with the. bottom centering. sleeve and the jacket an annular cavity for sealing-cement.

4. The invention according to claim 1, wherein the top centering sleeve includes an upwardly extending collar through which the top stem passes and wherein the said means maintaining the .top centering sleeve comprises: a centering yoke into which the collar snugly extends, outwardl-y and downwardly extending arms carried by the collar, and a centering ring-having the outer ends of the arms joined theretoandlsupported uponthe top of the mold.

. 5. Apparatus for casting tubular ingots, comprising an ingotxstooLan upright cylindrical mold thereon, a metal centering cone vertically posi+ tioned centrally in the mold withthe smaller end at thebottom, a flexible core encasing the cone, a

8 centering sleeve supported on the top of themold, said cone having an axial extension passing through the sleeve, means at the-top of the cone for facilitating lifting thecone and separating it from the flexible core to relieve the compressive force produced by the solidification of the hot metal on the flexiblecore, the top end of the cone entering the sleeve to a predetermined extent when the cone is lifted, means coupling thecone and sleeve after a predetermined extent of lift of the sleeve, and means coupling the bottom end of the cone with the coreafter the side face of the cone is separated from the core whereby the core, cone and sleeve form a unit to be lifted'as such from the tubular ingot casting in the mold.

6. Apparatus as set forth in claim 5, wherein the last named means comprises a body supported in the floor of thestool, thecore resting upon'said body and said last means-further including a lost motion coupling between the bottom end of the cone and said body.

7. Apparatus as set forth in claim 5, wherein the last named means includes a bottom sleeve removably positioned in a hole in the floor of the stool, the core resting at its bottom end upon the sleeve, and a bottom'axi'al stem extending down from the bottom end ofthe come through and having free sliding movement in the sleeve with means upon its lower end to engage the bottom end of and lift the sleeve and core rafter apredetermined movement of the cone.

BENJAMIN BROWNSTEIN.

"REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

